UNS: Fundamental studies of charge transfer states at organic donor-acceptor interfaces for photovoltaics

UNS：光伏有机供体-受体界面电荷转移态的基础研究

• 批准号: 1510481
• 负责人: Alberto Salleo
• 金额: $ 31.22万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1510481&HistoricalAwards=false
• 关键词: UNS; Fundamental; studies; charge; transfer

PI: Alberto SalleoProposal Number: 1510481The sun represents the most abundant potential source of sustainable energy on earth. Solar cells that use organic conducting polymers to convert light to electricity - organic photovoltaic (OPV) devices - offer a potentially low-cost route for renewable electricity production. However, in order to achieve parity with other solar photovoltaic technologies, organic solar cells must increase their power conversion efficiency past the current 10.5% world record. A principal reason for this low power output is that the electric charge transfer between the organic polymer that converts the sun's photons into electrons, and the nanostructured carbon which accepts the generated electron, does not work efficiently at the interface of these two materials. This proposed research will develop a fundamental scientific understanding of this process at the molecular level through advanced spectroscopic analysis techniques. The proposed educational activities include development of online videos for material science courses, and an undergraduate student project to use the spectroscopic methods developed in the research to characterize artifacts at the Cantor Arts Center at Stanford University. The goal of this research is to develop a fundamental understanding of the structure-property relationships for the donor-acceptor interface in organic polymer based photovoltaic (OPV) devices at the molecular level. The fundamental photocurrent generation mechanism in OPV involves splitting a tightly-bound electron-hole pair. Prior to the formation of separated charges, the electron transfer from the light absorbing polymer donor molecule to the electron acceptor molecule, typically fullerene or similar nanostructured carbon, generates a charge transfer state, where the electron and hole are formally on two different molecules and yet are still able to interact across the donor-acceptor interface. The solar energy conversion efficiency of OPV is due to low voltage generation, which is directly linked to energy of the charge transfer state, and it is hypothesized the disorder of the charge transfer state may be a causal factor. To better understand this process, model materials will be used to measure systematically how molecular orientation affects the energy of the charge transfer state. Towards this end, Fourier transform photocurrent spectroscopy will measure generated photocurrent, and a nanoscale electroluminescence technique will be developed to map the charge transfer state spatially and correlate it to well-known donor-acceptor interface configurations. Dilute ternary blends, where two mutually miscible fullerenes are blended with a low concentration of a donor polymer, will serve as model materials to investigate how compositional and structural disorder affects the energy of the charge transfer state. Complementary studies using donors with different degrees of aggregation will provide information on the dependence of this process on polymer aggregation and crystallinity. Overall, these studies will establish the structure-property relationships of the donor-acceptor interface and suggest new approaches for materials and interface design to increase voltage and power conversion efficiency of OPV devices. This fundamental knowledge may also provide insights on how to refine theoretical tools used to predict the performance and properties of organic polymer based optoelectronic materials. Research on OPV devices will be used to develop online video materials for an organic semiconductors course at Stanford University. The project will also involve undergraduate students to work with the Cantor Arts Center at Stanford University to spectroscopically characterize artifacts using the techniques developed in the proposed research.

PI：Alberto Salleopoposal编号：1510481太阳代表了地球上可持续能源最丰富的潜在来源。 使用有机导电聚合物将光转换为电力的太阳能电池 - 有机光伏（OPV）设备 - 为可再生电力生产提供了潜在的低成本途径。 但是，为了与其他太阳能光伏技术达成平等，有机太阳能电池必须提高其功率转换效率，超过当前10.5％的世界记录。 这种低功率输出的主要原因是，将太阳光子转换为电子的有机聚合物之间的电荷传递，并且接受产生的电子的纳米结构碳在这两种材料的界面上无法有效地工作。 这项拟议的研究将通过高级光谱分析技术在分子水平上对这一过程产生基本的科学理解。 拟议的教育活动包括开发材料科学课程的在线视频，以及一个本科生项目，用于使用研究中开发的光谱方法来表征斯坦福大学坎托艺术中心的人工制品。这项研究的目的是在分子水平的有机聚合物光伏（OPV）设备中对供体 - 受体接口的结构 - 受体界面进行基本了解。 OPV中的基本光电流产生机制涉及分解紧密结合的电子孔对。 在形成分离电荷之前，电子从光吸收聚合物供体分子转移到电子受体分子，通常为富勒烯或类似的纳米结构碳，会产生电荷转移态，其中电子和孔在两个不同的分子上正式在两个不同的分子上，但仍能够跨供体coppector-coppector-coppector-coppector-interface相互作用。 OPV的太阳能转化效率是由于低压产生引起的，该电压的产生直接与电荷转移状态的能量有关，并且假设电荷转移态的疾病可能是因果因素。 为了更好地理解这一过程，模型材料将用于系统地测量分子取向如何影响电荷转移状态的能量。 为此，傅立叶变换光电流光谱将测量产生的光电流，并将开发纳米级的电致发光技术以在空间上绘制电荷传输状态并将其与众所周知的供体 - 接受者接口构型相关联。 稀释三元混合物，其中两个相互可信的富勒烯与低浓度的供体聚合物混合在一起，将用作模型材料，以研究组成和结构障碍如何影响电荷转移状态的能量。使用不同程度聚集的供体的互补研究将提供有关该过程对聚合物聚集和结晶度的依赖性的信息。 总体而言，这些研究将建立捐赠者 - 受体界面的结构性质关系，并提出针对材料和界面设计的新方法，以提高OPV设备的电压和功率转换效率。 这种基本知识还可以提供有关如何完善用于预测基于有机聚合物的光学材料的性能和特性的理论工具的见解。 OPV设备的研究将用于开发斯坦福大学有机半导体课程的在线视频材料。 该项目还将涉及本科生与斯坦福大学的Cantor艺术中心合作，以使用拟议的研究中开发的技术来表征伪影。